Re: [PATCH 6/9] sunrpc: close connection when a request is irretrievably lost.

[Chuck Lever <chuck.lever@oracle.com>]

On 02/03/2010 05:20 PM, Trond Myklebust wrote:
> On Thu, 2010-02-04 at 08:23 +1100, Neil Brown wrote:
>> On Wed, 03 Feb 2010 10:43:04 -0500
>> Chuck Lever<chuck.lever@oracle.com>  wrote:
>>>
>>> I don't think dropping the connection will cause the client to
>>> retransmit sooner.  Clients I have encountered will reconnect and
>>> retransmit only after their retransmit timeout fires, never sooner.
>>>
>>
>> I thought I had noticed the Linux client resending immediately, but it would
>> have been a while ago, and I could easily be remembering wrongly.
>
> It depends on who closes the connection.
>
> The client assumes that if the _server_ closes the connection, then it
> may be having resource congestion issues. In order to give the server
> time to recover, the client will delay reconnecting for 3 seconds (with
> an exponential back off).
 >
> If, on the other hand, the client was the one that initiated the
> connection closure, then it will try to reconnect immediately.

That's only if there are RPC requests immediately ready to send, though, 
right?  A request that is waiting for a reply when the connection is 
dropped wouldn't be resent until its retransmit timer expired, I thought.

And, this behavior is true only for late-model clients... some of the 
eariler 2.6 clients have some trouble with this scenario, I seem to recall.

-- 
chuck[dot]lever[at]oracle[dot]com